Method of making hinge brackets

ABSTRACT

A method of making stamped and formed hinge brackets for tubular metal furniture and other metal stampings having circular (cylindrical) holes, featuring the formation of circular holes in the finished product by performing the steps of punching elliptical holes in a metal blank and then compressing the blank along the major axes of the elliptical holes in order to induce a flow of metal in the direction of the minor axes of said holes, thereby shortening the major axes and transforming the holes into circular configuration.

United States Patent n91 Kramer [54] METHOD OF MAKING HINGE BRACKETS [76] Inventor: Hyman Kramer, c/o Kramer Enterprise Inc., 1457 Basset Avenue, Stamford, Conn. 10461 [22] Filed: May 26, 1971 [21] Appl. No.: 143,710

[52] U.S. Cl 72/339, 72/377, 113/] 16 Y [51] Int. Cl B2ld 28/00 [58] Field of Search 72/339, 338, 377;

76/104R; 113/1 16 V, l16Y, 116 BB;408/l9;

[56] References Cited UNITED STATES PATENTS 2,182,067 12/1939 Bruecker ..76/104R June 19, 1973 Primary Examiner-Charles W. Lanham Assistant Examiner-Robert M. Rogers Att0rneySt0ll & Stoll [57] ABSTRACT A method of making stamped and formed hinge brackets for tubular metal furniture and other metal stampings having circular (cylindrical) holes, featuring the formation of circular holes in the finished product by performing the steps of punching elliptical holes in a metal blank and then compressing the blank along the major axes of the elliptical holes in order to induce a flow of metal in the direction of the minor axes of said holes, thereby shortening the major axes and transforming the holes into circular configuration.

8 Claims, 8 Drawing Figures HOLE 'PUNCHING STATION 1 TRINMING STATION 2 STA TION Z JLITTING STATION 4 FORMING STATION 5 PMENTED 3. 739.623

TRINHING STATION 2 I I .r'mrloua i 32 h mu JIH Jurruvs STATION 4 1}; v Ill! fORN/NG STATION 5 INVENTDR I/YNAN KRAMER BY w ATI'DlZ/VEVS PAIENTED J11?" 91975 3. 739 .623

SHEEIZIJFZ IN V NTOR. H YMA/V KRAMER METHOD OF MAKING HINGE BRACKETS BACKGROUND OF THE INVENTION l,528,5 87 Thackray 2,535,540 Lechmere 2,989,936 Famsworth et a1. 3 ,041 ,708 I-Ioltz 3,077,848 Hinsey 3,137,067 Bruecker Of the foregoing prior art patents, the closest appears to be Hinsey US. Pat. No. 3,077,848. Hinsey, however, uses the conventional method of punching a hole of a particular shape into a metal blank and then stretching the metal in order to change the shape of the punched hole to a different configuration. Stretching a metal blank to change the shape of holes punched therein is a very useful procedure in many applications. Hinsey illustrates but one such application. However, there are other applications in which stretching the metal will not achieve the desired result or for other reasons is not feasible. Illustrative is the hinge bracket which is shown in the present drawing. It has not been found feasible to apply the Hinsey stretching method to the formation of circular holes in this product.

SUMMARY OF THE INVENTION Briefly stated, the underlying principle of the present invention is the direct opposite of the stretch principle employed by Hinsey. Applicant has discovered that circular holes may be formed in stamped hinge brackets and other stampings by punching elliptical holes into a metal blank and, during the forming stage, compressing the metal along the major axes of these holes. The result is the formation of circular holes in the final product.

Not every geometrical form of ellipse will suffice for the purposes of this invention. Within the limitations imposed by the forming stage in the making of hinge brackets, a 40 ellipse has been found to be ideal. Other applications will require ellipses of greater or smaller angles. Naturally, the greater the angle the closer is the ellipse to a circular configuration, and the smaller is the compressive force required to convert the ellipse into a circle. An ellipse of less than 30 would be difficult, but not impossible, to transform into a circle. A 25 ellipse would be considered too small to be feasible. Of course, much depends upon such factors as the kind of material which is worked, its physical dimensions and proportions, its elasticity, and the length of the forming stroke required for shaping the final product. The length of that stroke must correspond to the length of the compression stroke required to convert an elliptical hole formed in such material to a circular hole. Conversely, the length of the product forming stroke should not-exceed the length of the stroke required to transform the elliptical hole to one of circular configuration, otherwise one ellipse, with reverse major and minor axes, would be substituted for another.

Taking a hinge bracket as an exemplification of the present invention, the procedure which is herein followed in making the bracket includes the steps of punching elliptical holes (using a 40 ellipse) into a metal blank and then forming the blank into a generally U-shaped bracket, the path of the forming stroke coinciding, substantially, with the major axes of the elliptical holes, and applying a compressive force upon the metal sufficient to transform the elliptical holes into circular holes.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view showing the succession of steps from the metal strip to the finished product, including the elliptical hole punching stage, the blank trimming stage, the blank slitting stage, the forming stage and the final cut-off stage.

FIG. 2 is a side view of the finished product as exemplified by a hinge bracket.

FIG. 3 is a similar view, but showing the opposite side thereof.

FIG. 4 is an end view of said hinge bracket.

FIG. 5 is a view of the blank from which the hinge bracket is made, showing the orientation of the elliptical holes and the directions of pressure applied to the blank in the forming operation to cause the flow of metal necessary to convert the elliptical holes to circular shape.

FIG. 6 is an enlarged fragmentary view of one portion of the blank of FIG. 5, showing one of the elliptical holes punched into said blank.

FIG. 6A shows a partial deformation of the metal resulting from the forming operation shortening the major axis and lengthening the minor axis of FIG. 6.

FIG. 6B shows the same hole in its final stage at the conclusion of the forming operation, the metal having been caused to flow to the extent required to equalize the major and minor axes of the elliptical hole and thereby to form a circular hole.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Hinge bracket 10 shown in the drawing exemplifies the present invention. It will be understood that this hinge bracket is used in tubular metal furniture and in other applications as well. In cross-section it has the configuration of an inverted U, consisting of a pair of spaced, generally parallel leg portions 12 and 14, respectively, joined by a yoke or bight section 16. Each of the leg portions has a pair of holes 18 formed therein, one at each lower comer. These are circular holes adapted to receive cylindrical rods or the like. Intermediate holes 18 on leg portion. 14 is a larger hole 20 which also has a circular configuration and is adapted to receive a cylindrical rod. In some hinge brackets of this general type a hole 20 is also formed in leg portion 12 in axial alignment with hole 20 in leg portion 14. The hinge bracket is also provided at its respective ends with a pair of angular shoulder portions 22 and 24, respectively. These shoulder portions serve a conventional purpose in the tubular furniture construction, e.g., they serve as limit or stop elements in the hinge arrangement. Hinge bracket 10 is essentially conventional in design and structure. The present invention is concerned not with the hinge bracket per se, but with the method of making it.

Hinge bracket is a metal stamping, being stamped and formed out of sheet or strip metal. In the preferred form of this invention multiple hinge brackets are concurrently made, for example in groups of three. The claimed process will now be described in terms of its application to the making of three hinge brackets at a time, but it will be understood that this is purely illustrative and the principles of this invention may be applied to the making of one hinge bracket at a time or any number of hinge brackets at a time, for example two or four.

The basic material used in the making of hinge brackets 10 is a metal strip 30 which is provided in long continuous coiled lengths. It will be seen that the claimed process involves the making of blanks, one for each hinge bracket, and, in the preferred form of this invention, metal strip 30 is wide enough for three such blanks.

In the first step of the claimed process, elliptical holes 32 are punched into metal strip 30 in the arrangement and with the orientation shown in the drawing. There are four elliptical holes 32 for each blank 34a, 34b and 340. Additionally, larger holes 36 are punched into metal strip 30, one or two such holes for each blank. In the illustrated form of the invention, only one hole 36 is formed in each of the blanks.

It will be observed that holes 32 are elliptical in configuration, and it will be understood that the preferred elliptical shape is a 40 ellipse. There are four elliptical holes 32 for each blank, and it will be seen that these holes occupy the four corners of the blank. Except for their slightly rounded or tapered ends, blanks 34a, 34b and 340 are essentially rectangular in plan view, and each elliptical hole 32 occupies or lies adjacent one of the corners of the rectangle.

It will also be observed that elliptical holes 32 are angled relative to each other and relative to the side and end edges of the blank in which they are formed. More specifically, each pair of elliptical holes 32 situated in diagonally opposite corners of the blank are oriented in such manner that their respective major axes lie substantially parallel to each other. Moreover, each elliptical hole 32 is disposed with its major axis lying at an angle of approximately 25 relative to the side edges 38, 40 of the blank. Stated differently, elliptical holes 32 are so oriented on their respective blanks 34a, 34b, 340 that the major axes of each diagonally opposite pair of such holes are substantially parallel to each other.

Hole 36 defines a 60 ellipse. its major axis is parallel to the side edges 38 and 40 of the blank and, consequently, at an angle of about 25 with respect to the major axes of elliptical holes 32.

In the performance of the process herein claimed, metal strip 30 is fed longitudinally (downwardly as viewed in FIG. 1) to a progressive die or series of dies (not shown), and the following sequence of operations ensures: At hole punching station 1, holes 32 and 36 are punched into the metal strip. As is indicated in the drawing, there are three sets of such punched holes for three side-by-side blanks. Following the hole punching operation, the metal strip is advanced to trimming station 2, where the forward or leading ends of the blanks are formed by punching scrap sections out of the metal strip. Spaces 30a, 30b, 30c and 30d are formed when the correspondingly shaped scrap sections of the metal strip are punched out. What is left is a series of narrow neck portions 31a, 31b and 31c between the portion of the metal strip which is situated at station 2 and the portion which projects ahead of it. When the strip is advanced to station 3, the scrap removal punching operation at station 2 is repeated and this, in effect, forms the trailing ends of the strip portion at station 3.

The metal strip is now advanced to slitting station 4, where it is slit longitudinally at lines 35 and 35a to form the three separate side-by-side blanks 34a, 34b and 340 above mentioned. These blanks are still connected to the metal strip by their respective neck portions 31a, 31b, 310 at their trailing ends.

At forming station 5, the three blanks are bent or formed into three hinge brackets 10 of inverted U shape. These formed hinge brackets are still connected to the blanks which precede them by means of their trailing neck portions. At cutting station 6 these neck portions are cut away and the finished hinge brackets 10 drop into a collecting bin or other receptacle.

It will of course be understood that the sequence of operations above described may be supplemented by providing spacing stations between the stations which are shown in the drawing. As an illustration, spacing stations may be provided between slitting station 4 and forming station 5, and between forming station 5 and cutting station 6.

The lines of force which transform the elliptical holes to circular configuration are shown in FIGS. 2, 3, 5, 6 and 6A of the drawing. Lines of force 50 coincide with and are also parallel to the major axes of elliptical holes 32. These lines of force are produced when the blanks are formed and, more particularly, they result from the pressure which is applied to form shoulders 22 and 24 of the hinge bracket. Secondary lines of force 50a may result from the same pressure, in line with lines of force 50, but generated on the opposite side of elliptical holes 32 in opposing direction. FIGS. 6 and 6A show how the forces represented by lines of force 50 and 50a cause the metal to flow and to squeeze the elliptical holes into circular configuration.

The same pressure exerted to form shoulders 22 and 24 also exerts forces against the larger elliptical hole 36, these forces being indicated in the drawing by lines of force 52 which coincide with and are parallel to the major axis of said hole. As is the case with the smaller elliptical holes 32, these forces cause the metal to flow and to squeeze the elliptical hole 36 into circular configuration.

The basic principle of this invention, as illustrated in the foregoing, resides in the formation of elliptical holes in a blank and orienting them in such direction (or directions) that their major axes coincide with (and are parallel to) the lines of force exerted in a forming operation, whereby the metal is caused to flow in such direction (or directions) as to squeeze the holes from elliptical to circular configuration.

It is intended that the foregoing description and accompanying drawings are to be taken as illustrative and not as limitative of the invention, and that modifications and variations of the invention are included within the scope of the appended claims.

As used herein, the terms forming and to form are intended to have the following conventional meaning as defined in Websters Third New International Dictionary, 1966, page 893: to bend or stretch (metal) to conform to the shape of a die or other tool. Forming operations, as herein referred to, are intended to consist of conventional forming or drawing operations, conventionally performed, on conventional power presses, such as conventional punch or stamping presses. In such forming operations the material is stretched in places and compressed in other places, and it is the object of the present invention to form circular or cylindrical holes in stamped metals by initially forming elliptical or oval holes and then compressing the metal along the longitudinal axis of these holes in order to transform them to circular or cylindrical configuration.

I claim:

1. A method of making stamped and formed metal hinge brackets and other metal stampings having circular holes, comprising the steps of:

a. punching elliptical holes in a metal blank,

b. forming the blank in the configuration of the final product, and, as part of the forming operation,

c. compressing the blank longitudinally of the major axes of the elliptical holes, and

d. causing the metal to flow in the direction of the minor axes of said holes,

e. thereby equalizing the major and minor axes and transforming the elliptical configuration of the holes to substantially circular configuration.

2. The method of claim 1, wherein:

a. the metal is caused to flow in such direction as to b. shorten the major axes,

c. lengthen the minor axes, and

(1. thereby equalize the major and minor axes to form substantially circular holes.

3. The method of claim 1, wherein:

a. the blank is formed in the configuration of the final product by applying forming pressure upon the blank in a single direction and at an acute angle relative to the major axes of the elliptical holes,

b. said forming pressure including relatively deep drawing pressure applied substantially in line with the major axes of said elliptical holes,

c. in order to cause the metal to flow longitudinally of said major axes and in the direction of the minor axes of said holes.

4. The method of claim 1, wherein elliptical holes in excess of 25 are punched into the metal blank.

5. The method of claim 1, wherein:

a. four elliptical holes are punched in a generally rectangular metal blank, one such hole in each corner thereof,

b. the major axes of diagonally oppositeholes being substantially parallel to each other,

c. forming the blank in the configuration of an inverted U-shaped final product, two of said elliptical holes being formed in one of the legs of said inverted U-shaped final product, and the other two elliptical holes being formed in the opposite leg thereof, and, as part of the forming operation,

d. deep drawing the ends of the bight of said inverted U-shaped final product,

e. to apply compressive forces longitudinally of the major axes of said elliptical holes, and

f. thereby causing the metal to flow in the direction of the minor axes of said holes,

g. in order to shorten the major axes and to transform the elliptical configuration of the holes to substan tially circular configuration.

6. The method of claim 5, wherein elliptical holes of 40 are punched into the metal blank.

7. The method of claim 1, wherein:

a. the elliptical holes are sequentially punched into a continuous metal strip having a width equal to the combined widths of a plurality of blanks arranged in side-by-side relationship,

b. each hole punching sequence providing elliptical holes for one transverse row of side-by-side blanks,

c. said metal strip being moved longitudinally of itself between punching sequences so that a succession of punching operations produces elliptical holes for successive transverse rows of blanks,

d. sequentially cutting said metal] strip, both longitudinally and transversely, to provide successive transverse rows of hole-punched blanks,

e. sequentially forming the successive transverse rows of hole-punched blanks in inverted U-shaped configuration,

f. thereby successively compressing the individual blanks of each transverse row to cause the metal to flow in the direction of the minor axes of the elliptical holes and to transform them into substantially circular holes.

8. The method of claim 7, wherein:

a. generally rectangular blanks are formed in the metal strip, and

b. four elliptical holes are punched in each blank, one

at each corner thereof,

c. said elliptical holes being oriented such that the major axes of the elliptical holes in diagonally opposite corners are disposed in parallel relationship and at an angle of approximately 25 relative to the sides of the blanks. 

1. A method of making stamped and formed metal hinge brackets and other metal stampings having circular holes, comprising the steps of: a. punching elliptical holes in a metal blank, b. forming the blank in the configuration of the final product, and, as part of the forming operation, c. compressing the blank longitudinally of the major axes of the elliptical holes, and d. causing the metal to flow in the direction of the minor axes of said holes, e. thereby equalizing the major and minor axes and transforming the elliptical configuration of the holes to substantially circular configuration.
 2. The method of claim 1, wherein: a. the metal is caused to flow in such direcTion as to b. shorten the major axes, c. lengthen the minor axes, and d. thereby equalize the major and minor axes to form substantially circular holes.
 3. The method of claim 1, wherein: a. the blank is formed in the configuration of the final product by applying forming pressure upon the blank in a single direction and at an acute angle relative to the major axes of the elliptical holes, b. said forming pressure including relatively deep drawing pressure applied substantially in line with the major axes of said elliptical holes, c. in order to cause the metal to flow longitudinally of said major axes and in the direction of the minor axes of said holes.
 4. The method of claim 1, wherein elliptical holes in excess of 25* are punched into the metal blank.
 5. The method of claim 1, wherein: a. four elliptical holes are punched in a generally rectangular metal blank, one such hole in each corner thereof, b. the major axes of diagonally opposite holes being substantially parallel to each other, c. forming the blank in the configuration of an inverted U-shaped final product, two of said elliptical holes being formed in one of the legs of said inverted U-shaped final product, and the other two elliptical holes being formed in the opposite leg thereof, and, as part of the forming operation, d. deep drawing the ends of the bight of said inverted U-shaped final product, e. to apply compressive forces longitudinally of the major axes of said elliptical holes, and f. thereby causing the metal to flow in the direction of the minor axes of said holes, g. in order to shorten the major axes and to transform the elliptical configuration of the holes to substantially circular configuration.
 6. The method of claim 5, wherein elliptical holes of 40* are punched into the metal blank.
 7. The method of claim 1, wherein: a. the elliptical holes are sequentially punched into a continuous metal strip having a width equal to the combined widths of a plurality of blanks arranged in side-by-side relationship, b. each hole punching sequence providing elliptical holes for one transverse row of side-by-side blanks, c. said metal strip being moved longitudinally of itself between punching sequences so that a succession of punching operations produces elliptical holes for successive transverse rows of blanks, d. sequentially cutting said metal strip, both longitudinally and transversely, to provide successive transverse rows of hole-punched blanks, e. sequentially forming the successive transverse rows of hole-punched blanks in inverted U-shaped configuration, f. thereby successively compressing the individual blanks of each transverse row to cause the metal to flow in the direction of the minor axes of the elliptical holes and to transform them into substantially circular holes.
 8. The method of claim 7, wherein: a. generally rectangular blanks are formed in the metal strip, and b. four elliptical holes are punched in each blank, one at each corner thereof, c. said elliptical holes being oriented such that the major axes of the elliptical holes in diagonally opposite corners are disposed in parallel relationship and at an angle of approximately 25* relative to the sides of the blanks. 